1. Field Of The Invention
The present invention relates to washing machines. More particularly, though not exclusively, the present invention relates to a method and apparatus for mounting an accelerometer in a washing machine for controlling machine vibration.
2. Problems In The Art
Washing machines have an inherent problem in that their dynamic systems rotate at high speeds, often producing excessive machine vibration. The dynamic system of the machine produces vibration which is transferred to the enclosure. This machine vibration typically becomes more problematic as the dynamic system increases rotational speed. For example, an unbalanced, rotating tub of a washing machine transfers the most vibration to the enclosure during the spin cycle.
Some prior art washing machines use an accelerometer to sense machine vibration. The accelerometer can provide feedback to a system that balances the tub to reduce vibration.
One type of accelerometer is made from a strip of piezoelectric film that acts as a cantilevered beam with a weight mounted on one end. The accelerometer converts the flex of the cantilevered beam into an acceleration reading.
One problem with piezoelectric film is that it often has a curvature that gives the beam a certain stiffness. This curvature varies from one piezoelectric film to another, causing a variation in sensitivities to acceleration and vibration. It is desired that the surface of the piezoelectric film remain flat and that the bending occurs in the most active area of the film, thereby improving the sensitivity and consistency of the accelerometer.
3. Features of the Invention
A general feature of the present invention is the provision of a method and apparatus for mounting a cantilevered piezoelectric film accelerometer which overcomes the problems found in the prior art.
A further feature of the present invention is the provision of a method and apparatus for mounting a cantilevered piezoelectric film accelerometer in a washing machine and the like, causing the surface of the piezoelectric film to flatten and thereby improve the sensitivity and consistency of the accelerometer.
A further feature of the present invention is the provision of a method and apparatus for mounting a cantilevered piezoelectric film accelerometer that ensures that the bending of the accelerometer occurs in its most active area, thereby further improving the sensitivity and consistency of the accelerometer.
A further feature of the present invention is the provision of a method and apparatus for mounting a cantilevered piezoelectric film accelerometer that is efficient in operation, economical to manufacture, and durable in use.
These as well as other features, objects, and advantages of the present invention will become apparent from the following specification and claims.